Studer J37 - C6 Capstan Assembly

,-
C
6
Capstan Assembly
The tape is driven
by the capstan which is connected to the
6
/
72
pole
hysterisis
synchronous
motor without intermediate
gearing.
The two
tape
speeds are achleved
by
swltchlng the
poles
of
the
motor.
A
heavy fly-wheel on the capstan is linked to the capstan motor by means of
an
elastic
coupling.
Mounted
on the same
frame,
which holds the capstan and the drive
motor,
is the capstan
pinch
-
roller with its swlvel arm
and
solenold. The
plnch-roller pressure
can be adjusted while the
machine is
runnlng through
a small opening ln the deck.
For measuring the
pinch-roller pressure,
the
fuse
S 2 should be removed in order to break the
capstan motor circuit. The
"playback"
button should
now
be
pressed
and before
making
any ad-
justments,
it should
be
ascertalned that
the
solenoid
has
pulled
right
in, so
that
the
pinch-roller
pressure
is controlled by the spring only and not by the solenoid. A spring-scale can now be
attached between
the rubber wheel
and its cover-plate.
The
pressure
should be approximately
1,800
q (4lbs
).
To remove or replace the
pinch-wheel,
unscrew the
aluminium
cover-plate, and simply lift it off.
Important:
The
above-mentioned
rubber wheel consists in the case of the
J
37, of two half-lnch wheels.
which
should
not be turned over nor swapped agalnst one another, 1. e . the upper wheel
should
notbemounted
in
place
of the lower one
or
vice versa
because
the wheels
are
ground
with
a sllght
taper
If
everything is correctly
adJusted,
the tape will
not
rub against the upper or lower edge of the
tape
gulde
on the head-block
(
beslde the
capstan
).
If
necessary, the entlre capstan assembly
may
be
removed. The
procedure
is
as
follows:
-
PulI rubber
pinch-roller
after
removing its mountlng
screw.
Undo the flxlng screw and
puII
plnch-wheel
bearing
off.
Disconnect the motor cable.
Undo
the three
screws
whlch hold the capstan assembly to the
deck-plate,
at
the
same time supportlng the capstan assembly
from underneath. When lowering
and
removlng the
capstan assembly,
care should be
taken that the
capstan ls
not
damaged.
If
necessary, the capstan itself
may
be
replaced.
It
runs
ln
two
special
preclsion
sleeve
bearings
and as
the fit is very crltical, it
should
be dlsmantled complete wlth lts bearlngs, and
replaced
by
an approprlate
preclsion-ground
and
tested
spare.
.l